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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 27, issue 2 | Copyright

Special issue: Ninth International Conference on Substorms (ICS9)

Ann. Geophys., 27, 861-868, 2009
https://doi.org/10.5194/angeo-27-861-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

  19 Feb 2009

19 Feb 2009


Low frequency eigenmodes of thin anisotropic current sheets and Cluster observations

L. M. Zelenyi1, A. V. Artemyev1, A. A. Petrukovich1, R. Nakamura4, H. V. Malova1,2, and V. Y. Popov1,3 L. M. Zelenyi et al.
  • 1Space Research Institute, Russian Academy of Sciences, Moscow, Russia
  • 2Nuclear Physics Institute, Moscow State University, Russia
  • 3Faculty of Physics, Moscow State University, Russia
  • 4Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Abstract. The eigenmodes of low frequency perturbations of thin anisotropic current sheets with a finite value of the normal magnetic field, are investigated in this paper. It is shown that two possible polarizations of symmetric and asymmetric modes (sausage and kink) exist where the growth rate of instabilities is positive. In addition, we demonstrate that a tearing instability might have a positive growth rate in thin anisotropic current sheets. The class of relatively fast wavy flapping oscillations observed by Cluster is described. The main direction of wave motion coincides with the direction of the current and the typical velocity of this motion is comparable with the plasma drift velocity in the current sheet. The comparison of these characteristics with theoretical predictions of the model of anisotropic thin current sheets, demonstrates that, in principle, the theory adequately describes the observations.

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